Devices of this type are described, for example, in the following U.S. Pat. Nos. 4,588,982, 4,655,359, and 4, 827,123, and in general they are well known in the prior art.
Such devices are used, in particular, for encoding the position and the direction of rotation of the disks in electric energy meters (i.e. "electricity meters"), and they generally use optical techniques, with each of the sensors comprising a light emitter and a light receiver, and with the modulator being constituted by an optical shutter suitable for optically isolating the light receiver from the corresponding light emitter, or not isolating it as a function of the position of the shutter.
Nevertheless, there is a problem in the prior art, for example when there is the need to be able to transmit information concerning the position and the direction of rotation of the disk to a distant point for remote meter-reading purposes.
Since, in a digital representation, the information concerned can be encoded on two bits only, the transmission of said information requires, a priori, the use of serial or parallel digital data transmission methods, both of which are too complex for the application concerned.
In addition, any transmission to a remote point includes the risk of information being lost, and thus the need to verify transmission quality.
In this context, an object of the present invention is to provide a device that is very simple and that is capable of transmitting data representing the position and the direction of rotation of a rotary element in a manner that is reliable and cheap.